A typical composite manufacturing process involves superimposing many layers of a fibrous loadbearing material (such as Fiberglas.RTM., Kevlar.RTM. or graphite fibers) onto a mold, impregnating the fibrous material with a bonding agent (such as epoxy), applying moderate pressure to the layup in the direction of the mold, and curing the resulting composite article at an elevated temperature.
One technique for applying pressure to the uncured composite article is to provide mating molds that sandwich the composite article therebetween, under mechanically-applied pressure.
Another technique for applying pressure to the uncured composite article, in the case of a single mold, is placing an airtight bag over the composite article, sealing the bag to the mold, and evacuating the bag. The surrounding atmosphere provides the applied pressure to the uncured composite article via the bag.
Silicone rubber vacuum bags have proven durable, but involve mechanically sealing the bag perimeter to the mold. Thus it has been known to use disposable bags (such as made from nylon) and to effect the bag perimeter to mold seal by inserting a semiadhesive sealer strip (such as Presstite.RTM.) therebetween. Presstite is a high temperature, medium pressure sealing agent. However, Pressite strips are not compatible with silicone rubber.